I returned for the first time in three years to the old Varsity multiplex — the Toronto International Film Festival’s longtime main press screening venue for years until its move to the downtown entertainment district — today for a private press screening of Jason Reitman’s “Labor Day,” which is utterly unlike the three previous films that hometown boy Reitman (his family donated the land for the TIFF Lightbox) premiered here, “Thank You For Smoking,” “Juno” and “Up in the Air.”

This small-scale gem, which Paramount is scheduled to begin rolling out stateside on Christmas Day, is part coming-of-age drama and part thriller, as well as being swooningly romantic. The protagonist, briefly played as an adult by Tobey Maguire...